It is inspiring that a piece of hardware launched in 1977 has now traversed the outer boundary of the solar system and has entered the reaches of interstellar space.

A story in The New York Times described the travels of Voyager 1, which NASA had sent into space on what was thought of as a four-year mission to explore Saturn. But the space probe kept on going, and last month it passed beyond the boundary of a region called the heliosphere. The heliosphere is the region of the solar system created by the collision of interstellar and solar winds. Beyond the heliosphere — the realm of our sun — space contains a plasma of ionized gases.

Let’s not pretend we know what any of that means. Astrophysics describes a realm of forces and particles whose names we may learn but whose nature is exceedingly difficult to grasp. We know about dark matter and the fact that it constitutes a high proportion of all the matter that exists. We are aware of a variety of particles that zip about in the universe, outside the solar system and within it, all of it connected to the forces of electromagnetism and light that are fundamental to existence. And don’t even mention the role that time plays in this complex, interwoven reality.

The layman grasps these physical realities with relative degrees of understanding. There are good books available explaining Einstein’s theory of relativity, as well as more recent discoveries about the universe. Some of us will work our way through these books, fascinated as much by the brilliance of the men and women able to plumb these mysteries as by the wondrous composition of the universe itself.

The physical discoveries of modern science exist in a realm so arcane that most of us take the conclusions of science on faith — faith that the scientists themselves know what they are doing and are subjecting their findings to the rigorous tests of the scientific method. For the layman, the signs bolstering our faith include the success of actual experiments, including continuing space exploration, such as the landing of the newest Mars rover. Scientists accomplish feats so astonishing we conclude that the theories upon which they are basing their work must be sound.

In a practical sense, one might ask what is to be gained from data about the nature of the plasma of interstellar space. (Terminology is always intriguing. Plasma, as a term, evokes the term “ether,” which was once used to describe the substance of the heavens. It seems that even in outer space there is never nothing.)

What is inspiring about the journey of Voyager 1, however, is not so much the data itself. Rather, the trajectory of the craft is something entirely new. Never has mankind sent an object beyond the solar system. The path of the craft is outward, like the path of knowledge itself. It is leading somewhere entirely new. It will tell us things we didn’t know, not for a utilitarian purpose, but for the purpose of knowing.

How much easier it would be to subside into ourselves, into the gravitational field of our own complacency, into the comfortable satisfaction of what we already know. And yet it is the outward trajectory of our knowledge that distinguishes us as a thinking, probing, exploring species. The paths of discovery have led humans to explore the far corners of our own planet.

We have burrowed deep into the mysteries of the organisms with which we share the planet, pushing back against our own ignorance about species of land, air and sea. We are burrowing ever deeper into the functioning of the human organism. And we continue to train our intelligence on the mysteries of the cosmos itself. How much simpler it might have been to believe that the sun was the center of the universe — until the truth got in the way. Now Voyager 1 is dipping its toe into the vast sea of space, telling us things we didn’t know before about regions beyond the reach of the sun.